Lizards

At each temple where you can save your game and heal yourself, look around for a Lizard with a white tail. If you kill them, you can eat their tail by pressing the R1 Button while standing next to them. Doing so will cause your strength meter to glow. In the demo, these made your strength go up. However, now it is much easier to just continue fighting the Colossi to make your strength increase. You can always find one in or around a save point. As you can see from the map, they are not only limited to the save shrines.